High-density disk recording medium having a protruding side on a clamping zone

ABSTRACT

The present invention relates to a high-density disk that is structured to prevent a collision of an optical pickup&#39;s objective lens with the high-density disk if the disk is placed upside down in a disk device that is able to record and reproduce signals to/from the high-density disk. A high-density disk recording medium according to the present invention is structured such that, wherein a recording layer having high-density pit patterns is offset from a center plane of disk thickness, both sides of a clamping zone bisected by the center plane have differing thicknesses. One or both sides may protrude from surface of the disk recording medium, or one side of the clamping zone may protrude from the surface while the other side is indented below the surface.

CROSS REFERENCE TO RELATED ART

[0001] This application claims the benefit of Korean Patent ApplicationNo. 2001-26250, filed on May 14, 2001, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a high-density disk structurepreventing collision of an optical pickup's objective lens with ahigh-density disk which is placed upside down in a disk device beingable to reproduce and record signals from/to a high-density disk such asa high-density digital versatile disk (called “HD-DVD” hereinafter).

[0004] 2. Description of the Related Art

[0005] A compact disk, usually called “CD,” is 1.2 mm in thickness and120 mm in diameter as shown in FIG. 1. A CD has a center hole of 15 mmdiameter and a clamping zone of 44 mm, which encircles the center holewhere the clamping zone is clamped by a damper on a spindle or aturntable installed in a disk device.

[0006] When a CD is normally placed into a disk device, its recordinglayer, which has pit patterns, is approximately 1.2 mm from an objectivelens of an optical pickup equipped in the disk device. The objectivelens for a CD has a numerical aperture (NA) of 0.45, which is relativelysmall.

[0007] A digital versatile disk, usually called “DVD,” is 1.2 mm inthickness and 120 mm in diameter like a CD as shown in FIG. 2. A DVDalso has a center hole of 15 mm diameter and a clamping zone of 44 mmencircling the center hole.

[0008] When a DVD is normally placed into a disk device, its recordinglayer, which has pit patterns, is approximately 0.6 mm from an objectivelens of an optical pickup equipped in the disk device. The objectivelens for a DVD has a NA of 0.6, which is relatively large.

[0009] A HD-DVD, which is currently being commercialized, is 1.2 mm inthickness and 120 mm in diameter, like a CD as shown in FIG. 3. A HD-DVDalso has a center hole of 15 mm diameter and a clamping zone of 44 mmencircling the center hole. If a ID-DVD is normally placed into a diskdevice, there will be a 0.1 mm gap between its recording layer, whichalso has pit patterns, and an objective lens of an optical pickup for aHD-DVD, which has the largest NA of 0.85. The optical pickup for aHD-DVD uses a laser beam of shorter wavelength than for a CD or a DVD torecord or reproduce signals in high density.

[0010] Therefore, in comparison with a CD or a DVD, HD-DVD uses anobjective lens that is situated closer to the recording layer, that usesa laser beam of shorter wavelength, and that has a greater NA. Accordingto these conditions, it is possible to concentrate a stronger intensityof light on a smaller beam spot formed on the high-density pit patternsof the recording layer of the HD-DVD. Consequently, the transmittingdistance of a laser beam of shorter wavelength is shortened, and thevariation of the laser beam and its spherical aberration are minimized.

[0011] If a HD-DVD 10 is normally placed onto a turntable 11 installedin a disk device as shown in FIG. 4, a conventional servo-controllingoperation for a spindle motor 12 by a motor driving unit 13 and a servocontroller 15 is conducted to rotate the placed HD-DVD 10 at a constantand high speed. While the HD-DVD 10 is rotating, a focusing-servooperation is conducted to focus a laser beam for an optical pickup 14exactly onto the recording layer 9. This operation is performed bymoving the objective lens OL of the optical pickup 14 in an up and downdirection within an operating distance OD. If a laser beam is exactly infocus, then reproduction (or recording) of high-density pit patterns canbe accomplished.

[0012] However, when the HD-DVD 10 is misplaced onto the turntable 11by, for example, being placed upside down as shown in FIG. 5, the HD-DVD10 will still be rotated at a constant and high speed by the combinedservo-controlling operation by the spindle motor 12, the motor drivingunit 13, and the servo controller 15. However, if the HD-DVD 10 has beenplaced upside down, the gap between the recording layer 9 and theobjective lens OL of the optical pickup 14 is 1.1 mm greater incomparison with a normally-placed HD-DVD.

[0013] In this misplacement, a laser beam cannot be focused within theconventional operating distance of the objective lens OL of the pickup14. Therefore, the servo controller 15 supervising the focusing-servooperation continues to move the objective lens OL upward to the maximummovable distance ‘OD_Max’ until the laser beam is correctly focused.However, in this case, the objective lens OL will collide with themisplaced HD-DVD 10. Consequently, the HD-DVD 10, the objective lens OL,and/or the servo-mechanism would be irreparably damaged.

SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide ahigh-density disk structured to prevent the collision of an objectivelens of an optical pickup and the high-density disk even though theobjective lens moves upward to maximum movable distance, and to enablethe detection of the misplacement of a high-density disk as no diskstate through a conventional focusing operation on the condition thatthe high-density disk has been placed upside down.

[0015] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the invention.The objectives and other advantages of the invention will be realizedand attained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0016] To achieve these and other advantages and in accordance with thepurpose of the present invention, as embodied and broadly described, arecording medium for storing data comprises a disk having first andsecond surfaces, the disk including a recording area and a clamping areaand defining a center hole for receiving a spindle therein, wherein theclamping area includes corresponding first and second clamping surfaces;a recording layer coplanarly disposed in the disk, wherein the recordinglayer is in closer proximity to the second surface of the disk; and theclamping area at least partially having a protruding portion on thefirst clamping surface so that the disk is raised from the spindle whenthe disk is inserted by placing the first clamping surface on thespindle.

[0017] According to one aspect of the present invention, the clampingarea at the protruding portion has first and second thicknesses measuredfrom a center plane of the disk, the first thickness measured in adirection extending from the center plane of the disk toward the firstsurface of the disk and the second thickness measured in a directiontoward the second surface, wherein the first thickness is greater thanthe second thickness. Preferably, the difference between the first andthe second thicknesses is approximately 0.1 mm to 0.6 mm.

[0018] According to another aspect of the present invention, the secondclamping surface is coplanar with the second surface of the disk.

[0019] According to another aspect of the present invention, theclamping area at least partially has a protruding portion on the secondclamping surface.

[0020] According to another aspect of the present invention, the secondclamping surface is at an uneven level with respect to the secondsurface of the disk.

[0021] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide a further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are included to provide afurther understanding of the invention, illustrate the preferredembodiments of the invention, and together with the description, serveto explain the principles of the present invention.

[0023]FIG. 1 shows the structure of a conventional compact disk (CD);

[0024]FIG. 2 shows the structure of a conventional digital versatiledisk (DVD);

[0025]FIG. 3 shows the structure of a conventional high-density DVD(HD-DVD);

[0026]FIGS. 4 and 5 show normal placement and misplacement of aconventional high-density DVD, respectively;

[0027]FIG. 6 is a sectional view of the first embodiment of, forexample, a high-density disk structured according to the presentinvention;

[0028]FIGS. 7 and 8 show normal placement and misplacement,respectively, of the first embodiment of a high-density disk structuredaccording to the present invention;

[0029]FIG. 9 is a sectional view of the second embodiment of ahigh-density disk structured according to the present invention;

[0030]FIGS. 10 and 11 show normal placement and misplacement,respectively, of the second embodiment of a high-density disk structuredaccording to the present invention;

[0031]FIG. 12 is a sectional view of the third embodiment of ahigh-density disk structured according to the present invention; and

[0032]FIGS. 13 and 14 show normal placement and misplacement,respectively, of the third embodiment of a high-density disk structuredaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] In order that the invention may be fully understood, a preferredembodiment thereof will now be described with reference to theaccompanying drawings.

[0034]FIG. 6 is a sectional view of the first preferred embodiment of ahigh-density disk structured according to the present invention. Theembodiment of a high-density disk, for example, a HD-DVD according tothe present invention has same dimension as a conventional HD-DVDdepicted in FIG. 3, namely, 1.2 mm in thickness and 120 mm in diameter,a center hole of 15 mm diameter and a clamping zone (or clamping area)of 44 mm diameter encircling the center hole. In addition, when thepresent HD-DVD 20 of FIG. 6 is normally placed into a disk device, itsrecording layer, which contains pit patterns, would be approximately 0.1mm from the objective lens of an optical pickup as mentioned before.

[0035] However, the present HD-DVD 20 in FIG. 6 has a clamping zonestructured such that the thickness (P1 and P2) of each side, P1 and P2,are different, namely and preferably P1 is greater than P2. P1 and P2are created by bisecting the clamping zone with an imaginarylongitudinal center plane “c.” In order for both sides to have differentthicknesses, the opposite side of the recording side, which is therecording layer, protrudes above the disk's upper surface, indicated byD1 in FIG. 6. Because it is not necessary for the entire clamping zoneto have a different thickness, the clamping zone may have partialregions that are protruding or raised with respect to the recording orreading area of the disk.

[0036] The height D1 preferably ranges from about 0.1 mm to 0.6 mm andguarantees a marginal gap between the present disk and the objectivelens for preventing a collision- between the objective lens of anoptical pickup even though the objective lens moves upward to themaximum movable distance on the condition that the present high-densitydisk has been placed upside down. Alternatively, other suitable heightD1 may also be used without deviating from the present invention.

[0037] If the disk 20 structured as above is placed normally on aspindle or turntable 11 equipped in a disk device as shown in FIG. 7,the non-protruding side of the clamping zone of the present disk 20 isin contact with the turntable 11. Consequently, the disk 20 is normallyclamped the same as a conventional disk.

[0038] After successful clamping of the high-density disk 20, aconventional servo-controlling operation, characterized by the operationof the spindle motor 12, the motor driving unit 13 and the servocontroller 15, is conducted to rotate the right-clamped disk 20 at aconstant and high speed. Subsequently, a focusing-servo operation isconducted to focus a laser beam exactly onto a recording layer by movingthe objective lens OL of the optical pickup 14 up and down within theoperating distance OD. Once the laser beam is exactly focused,reproduction (or recording) of the high-density pit patterns begins.

[0039] However, if the present disk 20 is placed upside down on theturntable 11 as shown in FIG. 8, the protruding side of the clampingzone of the present disk 20 is in contact with the turntable 11.Consequently, the surface of the disk 20 is raised by the height D1 overnormal placement, which ranges from about 0.1 mm to 0.6 mm. In otherwords, the separation distance between the objective lens and the disk20 has increased due to the added thickness of the clamping zone.

[0040] Therefore, although the objective lens OL of the optical pickup14 moves up to the maximum distance to acquire the exact focus while themisplaced disk 20 is rotating at a high speed, the objective lens OLwill not collide with the surface of the misplaced disk 20, due to themarginal gap D1 created by the protruding side of the clamping zone.Furthermore, because the recording layer, and the high-density pitpatterns contained within, is also further apart from the objective lensOL than in normal placement, the focusing operation will fail. As aresult, the misplacement of the disk would be judged as “no disk.”Because a judgment of “no disk” ceases the focusing operation, acollision between the objective lens OL and the disk 20 is avoided.

[0041]FIG. 9 is a sectional view of the second preferred embodiment of ahigh-density disk structured according to the present invention. Thesecond embodiment of a high-density disk 21 according to the presentinvention has a clamping zone structured such that the thickness of eachside, P1 and P2, which are created by bisecting the clamping zone withan imaginary longitudinal center plane “c,” are different. Namely, P1 isgreater than P2, where both P1 and P2 are both greater than one-half ofthe whole thickness of the disk 21 as shown in FIG. 9. The side oppositeto the recording side protrudes from disk surface a greater distancethan of the recording side. As shown in FIG. 9, the height D1, whichranges approximately from 0.1 mm to 0.6 mm, is greater than D2, which islocated on the recording side.

[0042] The protruding height D2 of the recording side is preferablydetermined to be within a range that ensures a successful focus of thepit patterns within the recording layer by the objective lens OL as itmoves up and down within the operating distance OD on the condition thatthe disk 21 has been normally placed.

[0043] Therefore, if the high-density disk 21 structured as above isplaced normally on the turntable 11, the recording layer of the disk 21is further apart from the objective lens OL by the small protrudingheight D2 than that of a conventional disk. However, because thedistance D2 is within a range ensuring successful focus as describedabove, it is possible to focus a light beam on the recording layer sothat reproduction (or recording) of the high-density pit patterns can beconducted.

[0044] If the high-density disk 21 is placed upside down on theturntable 11 as shown in FIG. 11, the surface containing the protrudingside of the clamping zone that measures in height D1 is situated higherby the same height D1, similar to the situation depicted in FIG. 8.Consequently, the objective lens OL of the optical pickup 14 can move upto the maximum distance to acquire an exact focus while the misplaceddisk 21 is rotating at a high speed without colliding with the surfaceof the misplaced disk 21. Also, because the recording layer is furtherapart from the objective lens OL by the height D1, the focusingoperation will fail, resulting in that the disk misplacement would bejudged as “no disk.” Because judgment of ‘no disk’ ceases all focusingoperations, a collision between the objective lens OL and the disk 21 isavoided.

[0045]FIG. 12 is a sectional view of the third preferred embodiment of ahigh-density disk structured according to the present invention. Thethird embodiment of a high-density disk 22 according to the presentinvention has a clamping zone structured such that the thickness of eachside, P1 and P2, which are created by bisecting the high-density disk 22with an imaginary longitudinal center plane “c.” In this case, P1 isgreater than P2 and P1 is thicker than one-half of the whole thicknessof the disk 22 but P2 is thinner than one-half of the whole thickness ofthe disk 22. The side opposite to the recording side protrudes from disksurface by the height D1, which ranges from approximately 0.1 mm to 0.6mm, whereas the clamping zone on the recording side is indented by aheight less than D1.

[0046] Therefore, if the high-density disk 22 structured as above isplaced normally on the turntable 11, the indented side of the clampingzone, which is in contact with a holder of the turntable 11, allows therecording layer of the disk 22 to be appropriately apart from theoptical pickup 14. However, the distance between the recording layer andthe objective lens OL for this embodiment is longer within theacceptable range for a conventional disk.

[0047] In this situation, an exact focus on the recording layer isacquired through moving the objective lens OL up and down within theoperating distance OD, which can then result in the reproduction (orrecording) of high-density pit patterns.

[0048] If the present disk 22 is placed upside down on the turntable 11as shown in FIG. 14, the surface of the disk 22 is raised by a heightD1, which ranges from 0.1 mm to 0.6 mm. Therefore, although theobjective lens OL of the optical pickup 14 can move up to the maximumdistance to acquire an exact focus on the recording layer, the objectivelens OL will not collide with the surface of the misplaced disk 22. Asdescribed above, the misplacement would result in a reading of “nodisk,” which would cease the focusing operation and avoiding a collisionbetween the objective lens OL and the disk 22.

[0049] In addition, the protrusion and/or indentation of the clamingzone may be shaped variously other than the aforementioned embodiments,for example, a clamping zone may be protruded or indented partially.

[0050] The invention may be applicable to a rewritable high-density diskas well as a read-only high-density disk without departing from thesprit or essential characteristics thereof. Alternatively, the presentinvention may also be applied to any other rewritable or read-only typedisk medium. The present embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims rather than by theforegoing description and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1.-22. (Canceled).
 23. An apparatus for recording or reproducing data onor from a recording medium, comprising: a driving unit rotating therecording medium, the recording medium having first and second surfaces,a clamping area including first and second clamping area, a center holefor receiving a spindle therein, and a recording layer disposed in alower portion with respect to center plane of the first and secondsurfaces, and being in closer proximity to the second surface, whereinthe clamping area having at least a protruding portion on the firstclamping surface so that the recording medium is raised from the spindlewhen the recording medium is inserted by placing the first clampingsurface on the spindle; a pickup unit that reads or records signals fromor to the recording medium; and a controller for controlling the drivingunit and the pickup unit.
 24. The apparatus of claim 23, wherein thecontroller controls the pickup unit so that the pickup unit does notcollide with a surface of the recording medium, if the recording mediumis placed upside-down in the apparatus.
 25. The apparatus of claim 24,wherein the controller outputs a signal to indicate that a focusoperation has failed when the recording medium is placed upside down inthe apparatus.
 26. An apparatus for recording or reproducing data on orfrom a recording medium, comprising: a driving unit rotating therecording medium, the recording medium comprising a first side having asurface, a second side having a surface, a recording layer disposedbetween the first side and the second side, and closely located at thesecond side, a first side clamping zone that is located concentricallywithin the first side and is level with the surface of the first side,and a second side clamping zone that is located concentrically withinthe second side and is unequal in thickness to the first side clampingzone; a pickup unit that reads or records signals from or to therecording medium; and a controller for controlling the driving unit andthe pickup unit.
 27. The apparatus of claim 26, wherein the controllercontrols the pickup unit so that the pickup unit does not collide with asurface of the recording medium, if the recording medium is placedupside-down in the apparatus.
 28. The apparatus of claim 27, wherein thecontroller outputs a signal to indicate that a focus operation hasfailed when the recording medium is placed upside down in the apparatus.29. An apparatus for recording or reproducing data on or from arecording medium, comprising: a driving unit rotating the recordingmedium, the recording medium comprising a clamping area, an informationarea having first surface and second surface, and a recording layerdisposed closely in the second surface, wherein a step from top surfacein the clamping area to the first surface in the information area isformed to have a different thickness in the recording medium; a pickupunit that reads or records signals from or to the recording medium; anda controller for controlling the driving unit and the pickup unit. 30.The apparatus of claim 29, wherein the controller controls the pickupunit so that the pickup unit does not collide with a surface of therecording medium, if the recording medium is placed upside-down in theapparatus.
 31. The apparatus of claim 30, wherein the controller outputsa signal to indicate that focus operation has failed when the recordingmedium is placed upside down in the apparatus.
 32. The apparatus ofclaim 29, wherein the controller controls an objective lens of thepickup unit to move upwardly to the maximum movable distance to focusthe recording layer when the first surface of the recording medium isplaced to bottom on the apparatus.
 33. The apparatus of claim 29,wherein the recording layer of the recording medium is located at about0.1 mm from the second surface, the controller controls the pickup unitto record or reproduce data on or from the recording layer of therecording medium.